Light emitting device

ABSTRACT

A light emitting device includes a semiconductor laser element and a base member. The base member includes a bottom part, a frame part, and first and second electrode layers. The frame part forms a frame surrounding the semiconductor laser element. An area within an intersection line between the first inner surface and the bonding surface of the frame part has a size larger than a size of the arrangement surface of the bottom part. An area within an intersection line between the second inner surface and the bonding surface of the frame part has a size smaller than the size of the arrangement surface. The planar surface of the frame part intersects at least a part of the second inner surface. The planar surface and the second inner surface form a step portion on an inner side of the frame. The second electrode layer is disposed on the planar surface.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No.2018-107569, filed on Jun. 5, 2018. The entire disclosure of JapanesePatent Application No. 2018-107569 is hereby incorporated herein byreference.

BACKGROUND 1. Technical Field

The present disclosure relates to a light emitting device.

2. Description of Related Art

A light emitting element package including a base part, which includes aframe and an upward-facing surface, and a light emitting element such asa LED element or a semiconductor laser element on the upward-facingsurface of the base part has been known. In addition, various materialscan be employed for a base member serving as a package body, andexamples of the materials include ceramics. JP 2014-68013 A describes alight emitting element package in which a light emitting element isdisposed on a surface of a package body formed by a ceramic layer.

SUMMARY

On the other hand, because a light emitting element such as asemiconductor laser element generates heat, heat dissipation is requiredto be considered when manufacturing a light emitting element package.The light emitting element package described in JP 2014-68013 A has astructure in which a light emitting element is disposed on a ceramic,and has room for improvement with regards to heat dissipation.

A light emitting device according to certain embodiments includes atleast one semiconductor laser element and a base member. The base memberincludes a bottom part, a frame part, and first and second electrodelayers. The bottom part contains a metal as a main material, and has anarrangement surface on which the semiconductor laser element isarranged. The frame part contains a ceramic as a main material, isbonded to the bottom part, and forms a frame surrounding thesemiconductor laser element. The frame part has a bonding surface, afirst inner surface, a second inner surface and a planar surface. Thebonding surface is bonded to a portion of the arrangement surface. Thefirst inner surface intersects the bonding surface around a periphery ofthe bottom part in a plan view. An area within an intersection linebetween the first inner surface and the bonding surface in the plan viewhas a size larger than a size of the arrangement surface. The secondinner surface intersects the bonding surface over the arrangementsurface. An area within an intersection line between the second innersurface and the bonding surface in the plan view has a size smaller thanthe size of the arrangement surface. The planar surface intersects atleast a part of the second inner surface, and is different from thebonding surface. The planar surface and the second inner surface form astep portion on an inner side of the frame. The first and secondelectrode layers is each electrically connected to the semiconductorlaser element. The second electrode layer is disposed on the planarsurface of the frame part.

According to certain embodiments of the present disclosure, a lightemitting device having good heat dissipation performance can beprovided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a light emitting deviceaccording to a first embodiment.

FIG. 2 is a schematic top view for illustrating an internal structure ofthe light emitting device according to the first embodiment.

FIG. 3 is a schematic cross-sectional view of the light emitting devicetaken along a line in FIG. 1.

FIG. 4A is a schematic perspective view for illustrating a method ofmanufacturing the light emitting device according to the firstembodiment.

FIG. 4B is a schematic cross-sectional view taken along a line BI-BI inFIG. 4A for illustrating the method of manufacturing the light emittingdevice according to the first embodiment.

FIG. 4C is a sectional view taken along a line BII-BII in FIG. 4A forillustrating the method of manufacturing the light emitting deviceaccording to the first embodiment.

FIG. 4D is a schematic perspective view of a bottom part of the lightemitting device according to the first embodiment.

FIG. 4E is a schematic top view of a frame part of the light emittingdevice according to the first embodiment.

FIG. 4F is a schematic bottom view of the frame part of the lightemitting device according to the first embodiment.

FIG. 5A is a schematic perspective view for illustrating the method ofmanufacturing the light emitting device according to the firstembodiment.

FIG. 5B is a schematic cross-sectional view taken along a line BI-BI inFIG. 4A for illustrating the method of manufacturing the light emittingdevice according to the first embodiment.

FIG. 5C is a schematic cross-sectional view taken along a line BII-BIIin FIG. 4A for illustrating the method of manufacturing the lightemitting device according to the first embodiment.

FIG. 6A is a schematic perspective view for illustrating the method ofmanufacturing the light emitting device according to the firstembodiment.

FIG. 6B is a schematic cross-sectional view taken along line BI-BI inFIG. 4A for illustrating the method of manufacturing the light emittingdevice according to the first embodiment.

FIG. 6C is a schematic cross-sectional view taken along line BII-BII inFIG. 4A for illustrating the method of manufacturing the light emittingdevice according to the first embodiment.

FIG. 7A is a schematic perspective view for illustrating the method ofmanufacturing the light emitting device according to the firstembodiment.

FIG. 7B is a schematic cross-sectional view taken along line BI-BI inFIG. 4A for illustrating the method of manufacturing the light emittingdevice according to the first embodiment.

FIG. 7C is a schematic cross-sectional view taken along line BII-BII inFIG. 4A for illustrating the method of manufacturing the light emittingdevice according to the first embodiment.

FIG. 8A is a schematic perspective view for illustrating the method ofmanufacturing the light emitting device according to the firstembodiment.

FIG. 8B is a sectional view on line BI-BI in FIG. 4A for illustratingthe method of manufacturing the light emitting device according to thefirst embodiment.

FIG. 8C is a schematic cross-sectional view taken along line BII-BII inFIG. 4A for illustrating the method of manufacturing the light emittingdevice according to the first embodiment.

FIG. 9A is a schematic perspective view for illustrating the method ofmanufacturing the light emitting device according to the firstembodiment.

FIG. 9B is a schematic cross-sectional view taken along line BI-BI inFIG. 4A for illustrating the method of manufacturing the light emittingdevice according to the first embodiment.

FIG. 9C is a schematic cross-sectional view taken along line BII-BII inFIG. 4A for illustrating the method of manufacturing the light emittingdevice according to the first embodiment.

FIG. 9D is a schematic top view of a substrate of the light emittingdevice according to the first embodiment.

FIG. 10A is a schematic view for illustrating the method ofmanufacturing the light emitting device according to the firstembodiment.

FIG. 10B is a schematic cross-sectional view taken along line BI-BI inFIG. 4A for illustrating the method of manufacturing the light emittingdevice according to the first embodiment.

FIG. 10C is a schematic cross-sectional view taken along line BII-BII inFIG. 4A for illustrating the method of manufacturing the light emittingdevice according to the first embodiment.

FIG. 11 is a schematic cross-sectional view of a light emitting deviceaccording to a second embodiment.

FIG. 12A is a schematic perspective view of a bottom part of the lightemitting device according to the second embodiment.

FIG. 12B is a schematic perspective view of the bottom part of the lightemitting device according to the second embodiment.

FIG. 13 is a schematic top view of a substrate of the light emittingdevice according to the second embodiment.

FIG. 14 is a schematic cross-sectional view of a light emitting deviceaccording to a first modified example.

FIG. 15 is a schematic cross-sectional view of a light emitting deviceaccording to a second modified example.

FIG. 16 is a schematic cross-schematic perspective view of a bottom partof the light emitting device according to the second modified example.

DETAILED DESCRIPTION OF EMBODIMENTS

Certain embodiments of the present invention will be described belowwith reference to the drawings. The embodiments shown below are intendedto embody the technical idea of the present invention, and are notintended to limit the scope of the present invention. Further, in thedescriptions below, the same names and reference numerals denote thesame or similar members, and detailed descriptions thereof are omittedas appropriate. The sizes, positional relationships and the like ofmembers shown in the drawings may be exaggerated for clarity ofdescription.

First Embodiment

FIG. 1 is a schematic view of a light emitting device 1 according to afirst embodiment, FIG. 2 is a top view for illustrating an internalstructure of a base member of the light emitting device, and FIG. 3 is asectional view taken along on line in FIG. 1. In FIG. 2, for showing theinternal structure, a cover 120, an adhesion portion 130 and a lensmember 140 are indicated by a broken line, and portions which are seenwhen viewed through the cover 120, the adhesion portion 130 and the lensmember 140 are indicated with a solid line. In addition, for avoidingcomplication of the drawings, a wire 180 as shown in FIG. 3 is omittedin FIG. 2.

In the light emitting device 1, light radiated from a plurality ofsemiconductor laser elements 170 is reflected by a light reflectingsurface of light reflecting members 150, and is emitted outside throughthe lens member 140. As shown in FIG. 2, three sub-mounts 160, on eachof which at least one of the semiconductor laser elements 170 isdisposed, are arranged, and the light reflecting members 150 aredisposed each corresponding to at least one of the semiconductor laserelements 170. Each of the plurality of semiconductor laser elements 170radiate light to a corresponding one of light reflecting members 150,and the corresponding light reflecting member 150 reflects light fromthe corresponding semiconductor laser element 170 toward the lens member140. The light emitting device 1 includes a package configured to emitlight, and a mounting substrate on which the package is mounted.Alternatively, a light emitting device without the mounting substratemay be considered as the light emitting device 1.

The light emitting device 1 includes a substrate 100 as the mountingsubstrate, and also includes a base member 110, the cover 120, theadhesion portion 130, the lens member 140, the light reflecting members150, the sub-mounts 160, the semiconductor laser elements 170, and thewires 180, which are constituent elements included in the package. Inaddition, in a sealed space formed by bonding the base member 110 to thecover 120, the light reflecting members 150 and the sub-mounts 160 oneach of which at least one of the semiconductor laser elements 170 isdisposed are arranged. Further, the wires 180 for electricallyconnecting semiconductor laser elements 170 disposed on the base member110 are provided. In addition, as shown in FIG. 3, the base member 110includes a frame part 111 and a bottom part 118.

The substrate 100 is bonded to the frame part 111 and/or the bottom part118. In addition, the frame part 111 is bonded to the cover 120 at aside opposite to a bonding surface bonded with the substrate 100. Thecover 120 is bonded to the lens member 140 with an adhesive agentdisposed therebetween. The adhesion portion 130 is formed bysolidification of the adhesive agent. A gap is created between the cover120 and the lens member 140 by forming the adhesion portion 130.Hereinafter, the light emitting device 1 will be described along withdescription of operations in manufacturing of the light emitting device1.

FIGS. 4A to 10A are schematic views for illustrating operations untilthe light emitting device 1 is obtained. In addition, FIGS. 4B to 10B or4C to 10C show schematic cross-sectional views in the steps so as tocorrespond to FIGS. 4A to 10A, respectively. FIGS. 4B to 10B areschematic cross-sectional views corresponding to line BI-BI shown inFIG. 4A. FIGS. 4C to 10C are schematic cross-sectional viewscorresponding to line BII to BII shown in FIG. 4A. Dotted lines S1 andS2 are not constituent elements of a light emitting element 2, butauxiliary lines for indicating correspondence in directions of the lightemitting device 2 in the respective drawings. In addition, an auxiliaryline in each cross-sectional view indicates a front side of thecross-sectional view, such that the auxiliary line in eachcross-sectional view corresponds to a corresponding one of the auxiliarylines in the schematic view in a corresponding one of FIGS. 4A, 5A, 6A,7A, 8A, 9A, and 10A. For example, the cross-sectional view of the basemember 110 in FIG. 5B with a line 51 is taken along a line correspondingto a line BI-BI in FIG. 4A, where the front face in FIG. 5B is at the S1line side of the base member 110 in FIG. 5A.

As shown in FIGS. 4A and 4D, the frame part 111 and the bottom part 118which form the base member 110 are provided. A metal such as Cu or Alcan be used for the bottom part 118, and a ceramic such as alumina(Al₂O₃) or AlN can be used for the frame part 111. Any appropriatematerial may be used for the bottom part 118, but at least, the bottompart 118 has a heat dissipation higher than that of the frame part 111,and the bottom part 118 has a thermal conductivity higher than that ofthe frame part 111.

The bottom part 118 includes a bonding surface bonded to the substrate100, and an arrangement surface on which the light reflecting member150, the sub-mount 160 and the semiconductor laser element 170 aredisposed. Each of the bonding surface and the arrangement surface has arectangular shape. In addition, the thickness from the bonding surfaceto the arrangement surface is substantially uniform. In the presentdisclosure, a rectangular shape with modified corners such as roundedcorners and/or slanted corners is also referred to as “a rectangularshape”. Similarly, a polygonal shape with rounded corners or the like isalso referred to as a “polygonal shape”. In addition, when a corner of arectangular shape or a polygonal shape is modified, the modified cornerportion is considered to be included in a corresponding side of therectangular shape or the polygonal shape. A surface bonded to thesubstrate 100 is considered as a bottom surface. The bonding surface ofthe bottom part 118 can be regarded as the bottom surface. The bottomsurface and the arrangement surface may alternatively have anyappropriate shapes other than the shapes described above.

The frame part 111 has a first electrode layer 112 at the bottomsurface, which is a surface bonded to the substrate 100. The firstelectrode layer 112 includes, for example, a metal layer, and is bondedto a metal film 103 of the substrate 100. Electric power is supplied tothe semiconductor laser element 170 through the metal film 103. Inaddition, the frame part 111 has a step portion inside the frame. Thestep portion included in the frame part 111 extends inward of the framepart 111, and a planar surface of the step portion at the bottom surface118 side is a bonding surface 113 bonded to the bottom part 118. Thus,the planar surface intersecting the inner surface 116 form a stepportion with the inner surface 116 on an inner side of the frame formedby the frame part 111. In the present specification, of two oppositeplanar surfaces, a planar surface closer to the substrate 100 isreferred to as a “lower surface”, and a planar surface opposite to thelower surface is referred to as an “upper surface”, for the sake ofconvenience. Alternatively, a planar surface closer to the lens member140 is referred to as an “upper surface”, and the surface opposite tothe upper surface is referred to as a “lower surface”. In FIG. 4A, theframe part 111 is arranged such that the upper surface faces downwardand the lower surface faces upward.

FIG. 4E is a top view of the frame part 111, and FIG. 4F is a bottomview of the frame part 111. The frame part 111 includes the bondingsurface 113 at a planar surface of the step portion 111 that is seen ina bottom view (that is, the lower surface of the step portion 111). Asecond electrode layer 114 to be electrically connected to asemiconductor laser element 170 is disposed at the planar surface of thestep portion that is seen in a top view (that is, the lower surface ofthe step portion 111). The planar surface intersects at least a part ofthe inner surface 117, and is different from the bonding surface 113.The second electrode layer 114 is electrically connected to the firstelectrode layer 112 through, for example, a via hole. The secondelectrode layer 114 includes, for example, a metal layer, and isarranged on a ceramic layer, and therefore is not exposed to the lowersurface of the step portion. Further, in the bottom view, the stepportion is disposed along all of the four sides of the frame part 111,but in the top view, the step portion is disposed along only three sidesof the four sides of the frame part 111, and is not disposed along theother one side of the four sides except for end portions overlapping twosides at both ends. That is, the region having the step portion in thetop view does not correspond to the region having the step portion inthe bottom view. For bonding of the bonding surface 113 of the stepportion to the bottom part 118, the step portion is disposed along theentire periphery of the frame part 111 in the bottom view. On the otherhand, the planar surface of the step portion that is seen in the topview has a region sufficient for disposing the second electrode layer,and is not necessarily disposed along the entire periphery.

In addition, the bonding surface 113 has a width along a side oppositeto a side not provided with the second electrode layer 114 larger than awidth of the bonding surface 113 along each of other sides of thebonding surface 113. On the other hand, a surface of the frame part 111bonded to the substrate 100 is designed such that a width along a sidenot provided with the second electrode layer 114 and a width along aside opposite thereto is the same. In other words, the shortest distancebetween a pair of opposite lateral surfaces of the frame part 111meeting the surface of the frame part 111 bonded with the substrate 100and the shortest distance between another pair of opposite lateralsurfaces of the frame part 111 intersecting the surface of the framepart 111 bonded with the substrate 100 are the same at correspondingpositions of each pair of opposite sides. The term “the same” as usedherein refers to that a difference between two or more values to becompared is within a design tolerance. With such a structure, a forceapplied to the base member 110 at the time of bonding the frame to thesubstrate 100 by soldering can be balanced. The term “correspondingpositions of each pair of opposite sides” as used herein refers to, withtwo sides opposite to and parallel to each other, a certain position inone of the two sides and a position in the other of the two sides withthe shortest distance therebetween.

Next, as shown in FIG. 5A, the bonding surface 113 of the frame part 111is bonded to the bottom part 118. For the bonding, for example, a silverbrazing material containing Ag as a main component and containing Cu canbe used, and other metal brazing materials can also be used. As shown inFIG. 4A, silver brazing material is applied to the bonding surface ofthe frame part 111 while the bottom surface of the frame part 111 facesupward, and the bottom part 118 is placed inside the frame of the framepart 111 with the silver brazing material melted by heating. The silverbrazing material is then cooled to bond the frame part 111 to the bottompart 118, so that the base member 110 is formed. The silver brazingmaterial is applied to a bonding region between the frame part 111 andthe bottom part 118, with the bonding region plated with Ni.

Thus, as shown in FIGS. 5B and 5C, the bonding surface of the bottompart 118 bonded to the frame part 111 has a size smaller than a size ofa frame formed by an inner surface 115 (first inner surface)intersecting the bottom surface of the frame part 111, and is locatedinward of the frame formed by the inner surface 115. In other words, theinner surface 115 intersects the bonding surface 113 around a peripheryof the bottom part 118 in a plan view, and an area within anintersection line between the inner surface 115 and the bonding surface113 in the plan view having a size larger than a size of the arrangementsurface of the bottom part 118. Further, the shapes of the inner surface115 of the frame part 111 and a lateral surface 119 of the bottom part118 are designed so that the arrangement surface of the bottom part 118is bonded to the bonding surface 113 at the step portion of the framepart 111. The light emitting device 1 according to the first embodimentis designed so that the height from the bottom surface of the frame part111 to the bonding surface 113 is the same as the height of the bottompart 118, and the periphery of the bottom part 118 is located inward ofthe frame formed by the inner surface 115 intersecting the bondingsurface 113.

Further, a gap is generated between the inner surface 115 and thelateral surface 119. As described above, the frame part 111 can beformed of a ceramic, and the degree of sintering in manufacturing maynot be constant. Thus, shapes and/or size of manufactured frame parts111 may be varied. In manufacturing of the light emitting device 1, withconsideration of design tolerance, the shapes of the frame part 111 andthe bottom part 118 are designed so as to generate a gap of 0.1 mmbetween the frame part 111 and the bottom part 118. The shapes of theframe part 111 and the bottom part 118 may be designed such that a gapof 0.1 mm or more or a gap of 0.1 mm or less is present.

The size of the gap is preferably in a range of 0.1 mm to 0.5 mm.Accordingly, the bottom part 118 can be properly bonded to the bondingsurface of the frame part 111, and the heat dissipation property of thebottom part 118 can be improved, so that the base member 110 excellentin heat dissipation property can be formed.

The size of the planar surface of the bottom part 118, which is bondedto the bonding surface 113, is larger than the size of a frame formed bythe step portion. More specifically, the size of the planar surface ofthe bottom part 118, which is bonded to the bonding surface 113 of theframe part 111, is larger than the size of the frame formed by an innersurface 116 (second inner surface) intersecting an inner end of thebonding surface 113, and the frame formed by the inner surface 116 iscovered with the bottom part 118. In other words, the inner surface 116intersects the bonding surface 113 over the arrangement surface, and anarea within an intersection line between the inner surface 116 and thebonding surface 113 in the plan view having a size smaller than the sizeof the arrangement surface.

In addition, the relationship between the frame formed by the innersurface 115 intersecting an inner end of the bottom surface of the framepart 111 and the frame formed by an inner surface 117 (second innersurface) intersecting an inner end of the upper surface of the framepart 111 is such that the width of the frame formed by the inner surface115 is larger than the width of the frame formed by the inner surface117 when seen in the S1 direction, and the widths of both frames are thesame as each other when seen in the S2 direction. In the S1 direction,there is a side along which the step portion for the second electrodelayer is not formed in top view, and the width of the frame at the lowersurface side is larger than the width of the frame at the upper surfaceside for forming the bonding surface at the side corresponding to theside along which the step portion is not formed.

In the S2 direction, both sides are provided with the step portion forthe second electrode layer, and therefore the bonding surface can beformed using a region corresponding to the step portion, so that thewidth of the frame at the lower surface side may not be larger than thewidth of the frame at the upper surface side.

Both sides of the frame part 111 when viewed in the S2 direction areprovided with the first electrode layer on the bottom surface of theframe part 111. Both sides of the frame part 111 when viewed in the S1direction are not provided with the first electrode layer on the bottomsurface of the frame part 111.

In view of a heat dissipation performance, it is preferable that thebottom part 118 have a large size. Meanwhile, when the width of thebottom surface of the frame part 111 is reduced, at the time ofperforming soldering, solder may be brought into contact with orconnected to both the first electrode layer and the bottom part 118.While the inner surfaces 115 and 117 are not required to have the samesize as each other when viewed in the S2 direction, the inner surface115 is located at a predetermined distance from the first electrodelayer. The position of the inner end of the bottom surface of the framepart 111 is determined with a spacing of 0.3 mm or more from the firstelectrode layer having a width of 0.5 mm. The first electrode layer 112is electrically connected to the second electrode layer 114 through aconductive portion provided inside the frame part 111.

An additional explanation will be given about determination of thestructures of the frame part 111 and the bottom part 118. In view of aheat dissipation performance, a material having a good heat dissipationis desired to be used for the bottom part 118 so that heat is diffusedfrom a position at which the semiconductor laser element 170, which is amain heat source, is arranged, so that a metal such as Cu is morepreferably used for the bottom part 118 than a ceramic. In addition, thebottom part 118 is preferably large at a certain degree, and it ispreferable that a portion exposed as an arrangement surface is made ofmetal. Further, for bonding the bottom surface 118 to the substrate 100,and effectively dissipating heat to the substrate 100 through the bondedportion, it is preferable that a material having poor heat dissipationis not disposed between the arrangement surface and the bonding surfacebonded with the substrate 100.

In addition, in view of strength, and shape stability at the time ofusing the light emitting device 1, it is preferable that the outer frameof the base member is made of ceramic. Further, in order to provide ametal layer for electrically connecting the semiconductor laser element,it is necessary to form a step portion at a part of the ceramic frame.Accordingly, the base member 110 in the light emitting device 1 isrequired to include at least: a frame that surrounds the periphery; abottom part on which a semiconductor laser is disposed; and a stepportion for providing a metal layer.

The step portion in a top view is not required to be provided over theentire inner periphery of the frame part 111, and a region to beprovided with the step can be appropriately adjusted according to thenumber of semiconductor laser elements 170 arranged in the lightemitting device 1, or a combination in arrangement of a plurality ofsemiconductor laser elements 170. For example, the step portion isprovided along one side or two sides of the frame part 111, or it may benecessary to provide the step portion over the entire periphery. The“combination in arrangement of a plurality of semiconductor laserelements 170” refers to, for example, a case where semiconductor laserelements having the same color and the same performance are disposed, ora case where semiconductor laser elements having different colors aredisposed.

With consideration of these, a metal is used for the bottom part 118while the frame part 111 is formed of a ceramic, so that interfacebetween the frame part and the bottom part is formed for improving theheat dissipation. Further, a gap is provided with consideration of adesign tolerance associated with a ceramic. Thus, it is possible toprovide the base member 110 having good heat dissipation compared to acase where the arrangement surface of the base member 110 on which thesemiconductor laser element 170 is disposed is formed of a ceramic.

In FIG. 6A, the light reflecting member 150, and the sub-mount 160 onwhich the semiconductor laser element 170 is arranged are bonded to thearrangement surface of the formed base member 110. The position at whichthe light reflecting member 150 and the sub-mount 160 are disposed isdetermined according to a position based on the frame part 111 ratherthan a position based on the bottom part 118. That is, the lightreflecting member 150 and the sub-mount 160 are disposed according to,rather than a distance or a coordinate from a specific position on thebottom part 118, a distance or a coordinate from a predeterminedposition on the frame part 111.

A gap is generated between the frame part 111 and the bottom part 118 asdescribed above, so that the bottom part 118 is movable in a frameformed by the frame part 111 before the bottom part 118 is fixed withthe frame part 111. Therefore, the bottom part 118 may move at the timeof performing bonding by brazing. For example, in the light emittingdevice 1, the shape of the frame of the frame part 111 is similar to theshape of the bonding surface of the bottom part 118, but as a result ofperforming bonding, the center points of the frame part 111 and thebottom part 118 may not correspond to each other, or the distancebetween the frame part 111 and the bottom part 118 may not be uniform.Therefore, it is preferable to adjust the arrangement position so thatthe position with respect to the frame part 111 is uniform for easilyperforming alignment between manufactured light emitting devices 1 evenwhen the bottom part 118 is misaligned. The smaller the gap between theframe part 111 and the bottom part 118, the smaller the misalignment dueto shifting.

The light reflecting member 150 has a light reflecting surface at one ormore surfaces. The light reflecting member 150 is irradiated with lightradiated from the semiconductor laser element 170, and therefore in thelight reflecting member 150, it is desirable that a material resistantto heat be used as a main material, and a material having a highreflectivity be used for the light reflecting surface. Glass such asquartz or BK7 (borosilicate glass), a metal such as aluminum, S1 or thelike can be employed as a main material of the light reflecting member150, and a metal, a dielectric multilayer film or the like can beemployed for the light reflecting surface. If necessary, in the lightemitting device 1, the light reflecting member 150 may have a pluralityof light emitting surfaces, or a light reflecting member may be disposedin addition to the light reflecting member 150. Further, a respectiveone of light reflecting members 150 is provided for a respective one ofsemiconductor laser elements 170, but one light reflecting member 150may be arranged for three semiconductor laser elements 170, or one lightreflecting member 150 may be provided for a plurality of semiconductorlaser elements.

For the sub-mount 160, aluminum nitride, or silicon carbide can be used.The sub-mount 160 is provided with a metal film, and the semiconductorlaser element 170 is fixed to the sub-mount 160 via an electricallyconductive layer of Au-Sn or the like.

The semiconductor laser element 170 is bonded to the sub-mount 160 atthe bottom surface thereof, and radiates light from a lateral surfacecloser to the light reflecting member 150. Laser light radiated from thesemiconductor laser element 170 has an elliptical far-field pattern(hereinafter, referred to as “FFP”) having a length in a layeringdirection of a plurality of semiconductor layers including an activelayer is larger than a length thereof in a direction perpendicular tothe layering direction, on a surface parallel to a light emitting endsurface.

The “FFP” as used herein refers to a light intensity distribution ofradiated light measured on a surface apart from the light emitting endsurface of the semiconductor laser element to a certain degree andparallel to the light emitting end surface. The shape of the FFP isspecified as a shape given by a main part of light. Here, the main partof light from the laser element refers to a part of laser light with anintensity range of a peak intensity value to any appropriate lowerintensity value such as 1/e².

The light emitting device 1 includes one or more semiconductor laserelements 170, and in FIGS. 6A to 6C, three semiconductor laser elements170 are disposed. The number of the disposed semiconductor laserelements 170 is not limited to 3, and may be 1 or more. Light emittedfrom these semiconductor laser elements 170 may have the same color, ordifferent colors. For example, the three semiconductor laser elements170 of the light emitting device 1 may include a first semiconductorlaser element which emits red light; a second semiconductor laserelement which emits green light; a third semiconductor laser elementwhich emits blue light.

The peak emission wavelength of red light is in a range of, for example,605 nm to 750 nm. Examples of the semiconductor laser element whichemits red light include those containing a semiconductor of InAlGaPtype, GaInP type, GaAs type or AlGaAs type. The peak emission wavelengthof green light is in a range of, for example, 495 nm to 570 nm. Examplesof the semiconductor laser element which emits green light includesemiconductor laser elements containing a nitride semiconductor. Thepeak emission wavelength of blue light is in a range of, for example,420 nm to 494 nm. Examples of the semiconductor laser element whichemits blue light include semiconductor laser elements containing anitride semiconductor. Examples of the nitride semiconductor includeGaN, InGaN and AlGaN.

In FIG. 7A, with wires bonded to the second electrode layer 114 in theframe part 111 and the semiconductor laser element 170, the secondelectrode layer 114 is electrically connect to the semiconductor laserelement 170. For example, using a wire bonding device, one end of an Auwire is bonded to the semiconductor laser element 170, and the other endis bonded to the second electrode layer 114. When a protective elementsuch as a Zener diode is arranged on the sub-mount 160, the protectiveelement is also electrically connected by the wire 180.

As shown in FIGS. 6A and 6B, the step portion for providing the secondelectrode layer 114 is provided along three sides in top view, and isnot provided along one side except for portions overlapping other sides.

The light reflecting member 150 is disposed between the one side alongwhich the step portion is not formed and the semiconductor laser element170 or the sub-mount 160, and the side along which the step portion isnot formed is located at a side opposite to the semiconductor laserelement 170 with the light reflecting member 150 disposed therebetween.Light radiated from the semiconductor laser element 170 is reflected bythe light reflecting member 150 to travel upward. As can be understoodfrom FIGS. 7A and 7B, if the side along which the step portion is notformed is provided with a step portion, and the second electrode layer114 on the side is electrically connected to the semiconductor laserelement 170 by the wire, the wire is present in a light travelingdirection, and thus blocks the light. In view of this, a step portionfor the second electrode layer 114 is not provided on a side at thelight reflecting member 150 side, and thus the second electrode layer114 can be appropriately disposed to allow reduction in the size of thelight emitting device 1.

In FIG. 8A, the frame part 111 of the base member 110 and the cover 120are bonded together to hermetically seal a space in which thesemiconductor laser elements 170 is arranged. For example, on the lowersurface of the cover 120, a region bonded to the base member 110 isprovided with a metal film, and the base member 110 is bonded and fixedto the cover 120 via AuSn or the like disposed therebetween. Thesemiconductor laser elements 170 are disposed in the closed space, sothat collection of organic substances and the like on the light emittingend surface of the semiconductor laser element 170 can be reduced.

For the cover 120, for example, glass provided with a metal film orsapphire provided with a metal film can be used, and in particular, itis preferable to use sapphire provided with a metal film. While spreadof light causes increase in size of a lens portion to transmit thelight, using sapphire for the lens portion of the lens member 140 allowsfor reducing degree of spread of light because sapphire has a relativelyhigh refractive index, so that the size of the lens portion of the lensmember 140 can be reduced. Further, sapphire has relatively highstrength, and is therefore hardly broken, so that hermetic reliabilityof a closed space can be secured.

In FIG. 9A, the base member 110 is mounted on the substrate 100. Thesubstrate 100 is bonded to the bottom surface of the frame part 111 andthe bottom part 118 of the base member 110. The bonding can be performedby soldering. As shown in FIGS. 9B and 9C, the substrate 100 includes aheat dissipation portion 101, an insulating portion 102 and the metalfilm 103. The heat dissipation portion 101 is formed of, for example, ametal such as Cu, the insulating portion 102 is formed of an insulatingmaterial, and the metal film 103 is formed of a metal such as Cusimilarly to the heat dissipation portion 101.

The heat dissipation portion 101 is bonded to the bottom part 118 of thebase member 110, and the metal film 103 or the insulating portion 102 isbonded to the frame part 111. Thus, the substrate 100 is designed suchthat the metal film 103 and the heat dissipation portion 101 areprovided on the same plane. More specifically, the heat dissipationportion 101 has a protruded structure protruded toward the base member110 in a cross-sectional view or a side view, and is formed so as to beexposed in a region bonded to the bottom part 118 of the base member110. On the other hand, in a region where the substrate 100 is bonded tothe frame part 111, the heat dissipation portion 101 does not protrude,and the heat dissipation portion 101 is not exposed by the insulatingportion 102 disposed on the heat dissipation portion 101. In a bondingregion of the substrate 100 that corresponds to a side of the frame part111 provided with the first electrode layer 112, the metal film 103 isdisposed on the insulating portion 102. Further, a predetermined spacingis provided between the heat dissipation portion 101 and the metal film103 so that the heat dissipation portion 101 and the metal film 103 arenot in contact with each other and electrically connected to each other.A part of the region provided with a predetermined spacing overlaps apart of the gap between the frame part 111 and the bottom part 118.

FIG. 9D is a top view of a bonding surface of the substrate 100 which isbonded to the base member 110. As shown in FIG. 9D, at the bondingsurface of the substrate 100, the substrate 100 includes the insulatingportion 102, the metal film 103, and an exposed portion 106 (aprotruding section having an exposed surface) in which the heatdissipation portion 101 is disposed. Further, the metal film 103includes metal regions 104 and an insulating region 105. The exposedportion 106 is bonded to the bottom part 118, and the metal regions 104is bonded to the bottom surface of the frame part 111.

The shape of the exposed portion 106 represents a region where the heatdissipation portion 101 protrudes. In addition, the shape of the exposedportion 106 corresponds to the shape of the bottom surface of the bottompart 118, and is designed to have a size slightly larger than a size ofthe bottom surface of the bottom part 118. If the size of the exposedportion 106 is equal to the size of the bottom surface of the bottompart 118, solder cannot expand outward of the bonding surface whensoldering, so that the solder may have an excessive thickness betweenthe substrate 100 and the base member 110. Further, in a top view, eachmetal region 104 includes two portions located at both sides of theinsulating region 105, Of the two portions of each metal region 104, aportion located closer to the center of the substrate 100 is bonded tothe frame part 111. By the bonding, each of the metal region 104 iselectrically connected to a corresponding first electrode layer 112.

With the metal films 103 and the exposed portion 106 of the heatdissipation portion 101 that are located at the same height, asdescribed above, it is possible to reduce lifting of the frame part 111or the bottom part 118 from the substrate 100 when bonding of thesubstrate 100 to the base member 110. If the degree of the lifting isincreased, bonding strength may be reduced, or a non-bonded region maybe partially formed, and therefore the possibility that detachment ofthe package from a mounting substrate occurs may be increased. Further,with the entirety of bottom surface of the bottom part 118 bonded to theexposed portion 106 of the heat dissipation portion 101, heat can beefficiently dissipated to the substrate 100.

In FIG. 10A, the lens member 140 is fixed to the cover 120 using anadhesive agent. By the adhering, the adhesion portion 130 is formedbetween the cover 120 and the lens member 140, and the light emittingdevice 1 shown in FIGS. 1 to 3 is obtained. The adhesion portion 130 isnot formed on the entire region of the upper surface of the cover 120 orthe entire region of the lower surface of the lens member 140, and isprovided at such a position where the adhesion portion 130 does notinterrupt a path of light emitted from the semiconductor laser element170. More specifically, in the light emitting device 1, a main part oflight emitted by the semiconductor laser element 170 is incident on andemitted from a region of the lens member 140 which has a lens shape.Therefore, it is desirable to use the adhesive agent such that theadhesion portion 130 is not formed on the lower surface of the lensmember 140 which corresponds to the region having a lens shape, and theadhesion portion 130 is formed in an outer peripheral region of the lensmember 140. It is preferable that an ultraviolet ray-curable resin isused for an adhesive agent that forms the adhesion portion 130. Anultraviolet ray-curable resin can be cured in a relatively short timewithout heating the resin, so that the lens member 140 is easily fixedat a desired position.

As shown in FIGS. 10B and 10C, the lens member 140 has a lens shape inwhich a plurality of lens portions is connected. Further, the lensmember 140 is designed such that one lens portion corresponds to onesemiconductor laser element, and such that lens portions transmit mainparts of light radiated from different semiconductor laser elements. Forthe lens member 140, for example, glass such as BK7 or B270 can be used.

The light emitting device 1 according to the first embodiment ismanufactured in the manner described above. The steps for manufacturingthe light emitting device 1 is not limited to the steps described abovewith reference to FIGS. 4A to 10A.

Second Embodiment

FIG. 11 is a sectional view of a light emitting device 2 according to asecond embodiment. The schematic view of the appearance of the lightemitting device 2 is not different from that in FIG. 1, and the internalstructure of the light emitting device 2 in top view is not differentfrom that in FIG. 2. The light emitting device 2 according to the secondembodiment is different from the light emitting device 1 according tothe first embodiment in the structure of a bottom part of a base member.In particular, in the second embodiment, the bonding surface of thebottom part, which is bonded to a substrate, is different from that inthe first embodiment. Thus, with an insulating portion and an exposedportion on the bonding surface of the substrate that have shapes adaptedto the bonding surface of the bottom part, structures, materials and thelike as described in the first embodiment can be employed for otherconfigurations.

As described in the step related to FIG. 5A for the light emittingdevice 1 of the first embodiment, it is desirable to dispose the bottompart 118 such that the distance between the frame part 111 and thebottom part 118 is entirely uniform at the time of bonding the framepart 111 to the bottom part 118. However, misalignment may occur in theprocess of bonding. If the degree of misalignment is great, a part ofthe bottom part 118 is brought into contact with the frame part 111.Further, if the spacing between the bottom part 118 and the frame part111 is narrower than a designed spacing, and accordingly the distancebetween the first electrode layer 112 and the bottom part 118 at thispart is reduced, then electrical connection may be established betweenthe first electrode layer 112 and the bottom part 118 at the time ofbonding the frame part 111 and the bottom part 118 to the substrate 100by soldering, which may lead to defectiveness of a light emittingdevice.

Thus, in the light emitting device 2 according to the second embodiment,a depressed portion 214 is formed on at least the outer edge of abonding surface 215 of a bottom part 213 bonded with a substrate 200.With this structure, the spacing between a frame part 211 and a bottompart 213 along a plane corresponding to the bottom surface, which is thebonding surface 215 bonded with the substrate 200, of a base member 210is greater than the spacing between the frame part 211 and the bottompart 213 along a plane corresponding to a bonding surface 212 bondedwith the frame part 211

FIGS. 12A and 12B show an example of the bottom part 213 having thedepressed portion 214. In one example, a protruded shape of the bottompart 213 forms a depression of the depressed portion 214. A protrudingregion having a protruded shape forms the bonding surface 215 bondedwith the substrate 200, and the bonding surface 215 may have a shapeobtained by scaling down a shape similar to the shape of an outer frameportion of the bottom part 213 as shown in FIG. 12A, or a circular shapeas shown in FIG. 12B. FIG. 13 is a schematic view showing a bondingsurface of the substrate 200 when the protruding region has a circularshape. As shown in FIG. 13, an exposed portion 201 has a circular shapein corresponding to the bonding surface 215 of the base member 210.

The depressed portion 214 has a spacing and height that sufficientlyallows for preventing occurrence of the above-described defect in a stepof soldering the base member to the substrate 200. For example, thelight emitting device 1 of the first embodiment is designed such that aspacing of about 0.1 mm is provided in the light emitting device 1, andthe depression may be designed so as to have a width of about 0.1 mm aslong as a spacing of at least about 0.1 mm may be provided. Thus, evenif the frame part 211 is in contact with a lateral surface of the bottompart 213 at the bonding surface 212 side bonded with the frame part 211,it is possible to maintain a spacing of about 0.1 mm between the framepart 211 and the bottom part 213 on the bonding surface bonded with thesubstrate 200. Further, for example, the light emitting device 1 of thefirst embodiment is designed such that the distance between the lateralsurface 119 of the bottom part 118 and the first electrode layer 112 is0.3 mm or more. When the width of the depression is designed, the widthof the depression may be similarly selected with consideration of thedesign of the frame part so that a distance of approximately 0.3 mm fromthe first electrode layer 112 is maintained. The spacing of 0.3 mm isone example in design of the light emitting device 1, and apredetermined spacing to be provided may be appropriately selectedaccording to the shape and materials of the light emitting device.

Therefore, the depressed portion 214 preferably has a width similar to awidth of a gap that would be secured when the bottom part 213 does nothave the depressed portion 214 and misalignment of the bottom part 213with respect to the frame part 211 does not occur. The depressed portion214 may have a width equal to or greater than a width of the gap, or mayhave such a shape that a part of the depression portion has a widthequal to or greater than a width of the gap, as in the bottom part 213in which the protruding region has a circular shape as shown in FIG. 12.However, because an increase in width of the depression leads to adecrease in bonding area with the substrate 200, it is desirable thatthe depressed portion 214 be prevented from having an excessively largewidth for attaining sufficient bonding, and the width of the depressedportion 214 is desirably 0.1 mm to 0.5 mm. For example, when a bondingsurface has a circular shape as shown in FIG. 12, the depressed portion214 may be designed such that the narrowest part of the depression has awidth similar to that of a gap to be secured.

Further, the depressed portion 214 secures a height that allows a solderextended out from the bonding surface 215 of the bottom part 213 bondedwith the substrate 200 to extend upward along a lateral surface meetingthe bonding surface 215 bonded with the substrate 200, and to beretained in the depression. The height of the depressed portion 214desirable to be secured is varied according to a material and an amountof solder to be used. For example, the depressed portion 214 secures aheight of about 0.2 mm in the light emitting device 2.

When the bonding surface bonded with the substrate has a rectangular orsquare shape with four modified corners, as in the bottom part 118described for the light emitting device 1 or the bottom part 213 shownas one example in FIG. 12, the exposed portion at the substrate side hasa shape according to the shape of the bonding surface, and accordingly,self-alignment occurs at the time of bonding the bottom part to thesubstrate.

On the other hand, when the bonding surface 215 bonded with thesubstrate 200 has a circular shape as in the bottom part 213 shown inFIG. 12B as one example, the exposed portion 201 at the substrate sidehaving a circular shape according to the shape of the bonding surfaceallows the bonding surface of the bottom part 213 to be located inwardof the outer periphery of the exposed portion 201. Further, with thebonding surface 215 and the exposed portion 201 having such circularshapes, even in a state where the bonding surface 215 and the exposedportion 201 are bonded with each other via a solder, the substrate 200and the bottom part 213 are movable along a rotating direction of thecircular shape until the solder is solidified. With the bonding surface215 bonded with the substrate 200 and having a circular shape, whenmisalignment occurs in arrangement of the frame part 211 and the bottompart 213, the arrangement can be adjusted in a rotating direction, sothat misalignment of the frame part 211 with respect to the substrate200 can be corrected.

First Modified Example

A light emitting device 3 according to a first modified example has astructure different from that in the light emitting device 2 shown inthe second embodiment, so as to obtain a light emitting device in whichthe spacing between a frame part and a bottom part along a planecorresponding to a bonding surface bonded with a substrate is greaterthan the spacing between the frame part and the bottom part along aplane corresponding to a bonding surface bonded with the frame part.

FIG. 14 is a cross-sectional view of the light emitting device 3according to the first modified example. As shown in FIG. 14, in thelight emitting device 3, a depressed portion 312 is formed in a framepart 311, so that the spacing between the frame part 311 and a bottompart 313 along a plane corresponding to a bonding surface bonded with asubstrate 300 is greater than the spacing between the frame part 311 andthe bottom part 313 along a plane corresponding to a bonding surfacebonded with the frame part 311. In other words, a size of the areawithin the intersection line between the inner surface of the frame part311 and the bonding surface is smaller than a size of an area within anintersection line between the inner surface of the frame part 311 andthe bottom surface of the frame part 311 in the plan view. The lightemitting device 3 may be produced by a method including processing theshape of the frame part 311 as described above, and in the lightemitting device 3, the substrate 100 in the first embodiment can beemployed as such unlike the light emitting device 2.

Second Modified Example

FIG. 15 is a cross-sectional view of a light emitting device 4 accordingto a second modified example. In addition, FIG. 16 is a schematic viewof a bottom part according to the second modified example. As shown inFIG. 15, the light emitting device 4 includes a bottom part 412, inwhich a bonding surface bonded with a substrate 400 has a size smallerthan a size of a bonding surface bonded with a frame part 411 at abottom part 412, and a lateral surface 413 is inclined. With inclinationof the lateral surface 413 as described above, the spacing between theframe part 411 and the bottom part 412 on the bonding surface bondedwith the substrate 400 can be greater than the spacing between the framepart 411 and the bottom part 412 at the bonding surface bonded with theframe part 411. Instead of inclination of the bottom part 412, the framepart 411 may be provided with inclination as in the first modifiedexample.

Certain embodiments and modified examples of the light emitting deviceaccording to the present invention has been described above, but thelight emitting device for implementing the technical idea of the presentinvention is not limited to these embodiments and modified examplesdescribed above. For example, while a light emitting device in whichthree semiconductor laser elements are arranged has been described, oneor more semiconductor laser elements may be arranged in the lightemitting device. Also, the light emitting device may not include thelight reflecting member 150 so that light radiated from a semiconductorlaser element travels in a direction of the lens member 140.

In addition, the light emitting device having configurations describedin the present disclosure is not limited to the structures of the lightemitting devices 1 to 4. For example, the present invention can beapplied even to a light emitting device having a constituent elementwhich is not illustrated in descriptions of any of the light emittingdevices 1 to 4, and having difference in a structure from a structure inthe light emitting device as described above cannot be a ground forfailure to apply the present invention.

On the other hand, the present invention can be applied withoutnecessity of sufficiently including all constituent elements of thelight emitting device described in the embodiments and modified examplesabove. For example, when some constituent elements of the light emittingdevice disclosed in the first embodiment are not described in claims,the constituent elements which are not described in claims may have anyappropriate structure, and the freedom of design thereof such asreplacement, omission, modification of the shape, change of materials,and the like by a person skilled in the art is accepted, with whichapplication of the invention is claimed.

The light emitting device described in certain embodiments can be usedfor projectors, on-vehicle headlights, illuminations, backlights ofdisplay devices, and the like.

What is claimed is:
 1. A light emitting device comprising: at least onesemiconductor laser element; and a base member including: a bottom partcontaining a metal as a main material, and having an arrangement surfaceon which the semiconductor laser element is arranged, a frame partcontaining a ceramic as a main material, bonded to the bottom part, andforming a frame surrounding the semiconductor laser element, the framepart having a bonding surface bonded to a portion of the arrangementsurface, a first inner surface intersecting the bonding surface around aperiphery of the bottom part in a plan view, an area within anintersection line between the first inner surface and the bondingsurface in the plan view having a size larger than a size of thearrangement surface, a second inner surface intersecting the bondingsurface over the arrangement surface, an area within an intersectionline between the second inner surface and the bonding surface in theplan view having a size smaller than the size of the arrangementsurface, and a planar surface intersecting at least a part of the secondinner surface, and being different from the bonding surface, the planarsurface and the second inner surface forming a step portion on an innerside of the frame, and first and second electrode layers eachelectrically connected to the semiconductor laser element, the secondelectrode layer being disposed on the planar surface of the frame part.2. The light emitting device according to claim 1, wherein the secondinner surface has a region intersecting the bonding surface and theplanar surface, and a region intersecting the bonding surface, and notintersecting the planar surface.
 3. The light emitting device accordingto claim 1, wherein the base member has a bottom surface on a sideopposite to the arrangement surface, each of the bottom part and theframe part has a bottom surface such that the bottom surface of thebottom part and the bottom surface of the frame part correspond to thebottom surface of the base member, and a gap is present between thebottom surface of the bottom part and the bottom surface of the framepart.
 4. The light emitting device according to claim 3, wherein a gapis present between a lateral surface of the bottom part and the firstinner surface of the frame part over a region ranging from the bondingsurface to the bottom surface of the base member.
 5. The light emittingdevice according to claim 3, wherein the frame part has a quadrangularshape in the plan view, and the bottom surface of the frame part has twoopposite sides having the same width, and two adjacent sides havingdifferent widths.
 6. The light emitting device according to claim 3,wherein the first electrode layer is disposed on the bottom surface ofthe frame part, the bottom surface of the frame part has a polygonalshape in the plan view, and the bottom surface of the frame part has aside provided with the first electrode layer and a side not providedwith the first electrode layer, such that the side provided with thefirst electrode layer has a width larger than a width of the side notprovided with the first electrode layer.
 7. The light emitting deviceaccording to claim 3, wherein the gap between the lateral surface of thebottom part and the first inner surface is larger along a planecorresponding to the bottom surface than along a plane corresponding tothe bonding surface.
 8. The light emitting device according to claim 7,wherein the bottom surface of the bottom part has a size smaller than asize of the arrangement surface.
 9. The light emitting device accordingto claim 8, wherein the bottom part has a depressed portion at an outeredge of the bottom surface of the bottom part.
 10. The light emittingdevice according to claim 8, wherein the bottom part further has alateral surface inclined from the arrangement surface to the bottomsurface of the bottom part.
 11. The light emitting device according toclaim 7, wherein in the frame part, the size of the area within theintersection line between the first inner surface and the bondingsurface is smaller than a size of an area within an intersection linebetween the first inner surface and the bottom surface of the frame partin the plan view.
 12. The light emitting device according to claim 3,wherein the bottom surface of the bottom part has a circular shape. 13.The light emitting device according to claim 3, further comprising asubstrate including an insulating portion, and a heat dissipationportion including a protruding section having an exposed surface exposedfrom the insulating portion, the protruding section having a protrudedshape in a cross-sectional view, the exposed surface having a shapecorresponding to a shape of the bottom surface of the bottom part in theplan view, and the exposed surface being bonded to the bottom surface ofthe bottom part.